
        *{
            margin: 0;
            padding: 0;
        }
        .head{
            width: 100%;
            height: 50px;
            background-color: rgb(51, 51, 51);
        }
        .center{
            width:80%;
            height: 800px;
            margin:  0 auto;
        }
        .center h3{
            text-align: center;
            font-weight: normal;
            margin-top: 10px;
            border-bottom: 1px solid gray;
            height: 40px;
            line-height: 40px;
            margin-bottom: 30px;
          
        }
        .left{
            width: 15%;
            height: 300px;
            background-color: #f5f5f5;
            float: left;
            padding: 20px;
        }
        
        .left p{
            padding: 8px 0;
            cursor: pointer;
           position: relative;
        }
        .left .p1 {
        font-weight: 500;  
    }
    .left .p1 ~ p::before { 
        content: "•";
        color: #666;
        position: absolute;
        left: 0.5em;       
        top: 50%;
        transform: translateY(-50%);
    }
    .left .p1 ~ p:not(:last-child) { 
        border-bottom: 1px solid #eee; 
        margin-bottom: 4px;          
    }

        .left .p1 ~ p{ 
        padding-left: 2em;  
    }
        .left .p2 {
        color: #ff4444;   
        font-weight: 500;
    }
        .right{
            width: 78%;
            height: 100%;
            float: right;
            padding: 20px;
            position: relative;
        }
        .foot{
            width: 100%;
            height: 70px;
            background-color: rgb(51, 51, 51);
            color: white;
            font-size: 14px;
            text-align: center;
            line-height: 70px;
            float:right;
        }
        .search{
            width: 100%;
            height: 40px;
            line-height: 40px;
            margin-bottom: 8px;
            position: relative;
        }
        .search input{
            height: 35px;
            line-height: 35px;
            font-size: 14px;
            border: 1px solid #ddd;
            outline: none;
            padding: 0 15px;
            border-radius: 20px;
            width: 200px;
            float: right;
            padding-right: 40px; 
            width: 240px; 
        }
        .search::after {
        content: "🔍";
        position: absolute;
        right: 15px;
        top: 50%;
        transform: translateY(-50%);
        cursor: pointer;
        opacity: 0.6;
        transition: opacity 0.3s;
    }
    .search:hover::after{
        opacity: 1;
    }
        .content{
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            gap: 20px;
        }
        .item{
            background: #fff;
            padding: 10px;
            display: flex;
            flex-direction: column;
            align-items: center;

        }
        .item img{
            width: 100%;
            height: 100%;
            margin-bottom: 10px;
        }
        .page{
            position: absolute; 
        left: 50%;          
        transform: translateX(-82%)translateY(-78px);
        bottom: 20px;      
        white-space: nowrap; 
        }
        .content{
            margin-bottom: 60px;
        }
        .page button{
            padding: 6px 10px;
            margin: 0 2px;
            border: 1px solid #ddd;
            background: #fff;
            cursor: pointer;
            transition: all 0.3s;
        }
        .page button:first-child{
            color: #ff4444 !important;
            border-color:#ff4444 !important;
            font: weight 500;
        }
        .page button:hover{
            background: #f8f8f8;
        }
        .page button:first-child:hover {
        background: #ffecec;
        }

.auth-buttons {
  position: absolute;
  right: 20px;
  top: -50px; /* 根据标题高度调整 */
  display: flex;
  gap: 8px;
}

.auth-btn {
  padding: 4px 12px;
  border: 1px solid #ddd;
  background: #fff;
  border-radius: 12px;
  font-size: 14px;
  cursor: pointer;
  transition: all 0.3s;
  color: #666;
  display: inline-block;
    text-decoration: none; 
    text-align: center;
    min-width: 60px; 
}

.auth-btn.login {
  color: #ff4444;
  border-color: #ff4444;
}

.auth-btn:hover {
  background: #f8f8f8;
  color: #333;
}

.auth-btn.login:hover {
  background: #ffecec;
  border-color: #ff6666;
}

/* 调整标题容器定位 */
.center h3 {
  position: relative;
  padding-right: 180px; /* 给按钮留出空间 */
}
/* 全局更新 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', sans-serif; /* 更现代字体 */
}

/* 头部改造 */
.head {
    background: linear-gradient(135deg, #ff6b6b, #ff4444); /* 渐变红色 */
    box-shadow: 0 2px 15px rgba(255, 68, 68, 0.2);
    height: 60px;
    display: flex;
    align-items: center;
    padding: 0 30px;
}

/* 主内容区 */
.center {
    width: 85%;
    max-width: 1200px;
    margin: 30px auto;
    padding: 20px;
    background: #fff;
    border-radius: 15px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.08); /* 柔和阴影 */
}

/* 标题样式统一 */
.center h3 {
    color: #333;
    font-size: 24px;
    padding: 0 0 15px;
    border-bottom: 2px solid #ff4444; /* 红色下划线 */
    margin-bottom: 30px;
    position: relative;
}

/* 左侧导航升级 */
.left {
    background: #fff;
    border-radius: 12px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.08);
    padding: 15px !important;
    transition: transform 0.3s ease;
}

.left:hover {
    transform: translateY(-3px);
}

.left p {
    padding: 12px;
    margin: 8px 0;
    border-radius: 8px;
    transition: all 0.3s ease;
}

.left p:not(.p1):hover {
    background: #fff5f5;
    transform: translateX(5px);
}

.left .p1 {
    color: #ff4444;
    font-weight: 600;
    font-size: 16px;
    border-bottom: 2px solid #eee;
}

/* 课程卡片升级 */
.item {
    background: white;
    border-radius: 12px;
    padding: 15px;
    box-shadow: 0 3px 12px rgba(0,0,0,0.08);
    transition: all 0.3s cubic-bezier(0.4,0,0.2,1);
    overflow: hidden;
    position: relative;
}

.item:hover {
    transform: translateY(-5%);
    box-shadow: 0 8px 20px rgba(255, 68, 68, 0.15);
}


/* 搜索框 */
.search input {
    border-radius: 25px;
    border: 2px solid #ffd4d4;
    padding: 0 20px;
    transition: all 0.3s ease;
}

.search input:focus {
    border-color: #ff4444;
    box-shadow: 0 0 15px rgba(255, 68, 68, 0.2);
}

.search::after {
    right: 20px;
    opacity: 0.8;
}

/* 分页按钮 */
.page button {
    border-radius: 8px;
    background: #fff;
    border: 2px solid #ffd4d4;
    color: #666;
    transition: all 0.3s ease;
}

.page button:first-child {
    background: #ff4444;
    color: white !important;
    border-color: #ff4444;
}

.page button:hover {
    background: #fff5f5;
    border-color: #ff4444;
    color: #ff4444;
}

/* 底部升级 */
.foot {
    background: linear-gradient(135deg, #ff6b6b, #ff4444);
    margin-top: 50px;
    box-shadow: 0 -2px 15px rgba(255, 68, 68, 0.2);
    font-size: 14px;
    letter-spacing: 0.5px;
}